There's some confusion about how new the D614G mutation is. I'm going to use data on @GISAID visualized by @CovidCg to answer this question. The first time it appeared in China was Jan 23, 2020. So this mutation occurred pretty early on in the outbreak before travel restrictions. 
When+where did D614G first get detected in Europe? It's not possible to tell using GISAID alone because many countries did not sequence virus isolates and deposit data till later in the pandemic. However, you can see that there are EU countries with D614G even in Jan.
It was only after January that travel restrictions started being sporadically imposed on China by other countries but it was too late because SARS2 (including D614G variants), as we now know, was already widespread. thinkglobalhealth.org/article/travel…
Had to remove the UK from the "Compare Locations" analysis in Europe because of how many sequences they've uploaded - just a tsunami that washes out the sequences from other countries. The G614 variants, in blue, are among the earliest sequences found in the UK, including in Jan.
Other European countries saw similar trends as well - D614G was among their earliest sequenced virus isolates and quickly became the more prevalent mutation at that point in the Spike. E.g., Germany shown here, G614 in blue, D614 in grey
Netherlands, G614 variants shown in blue, D614 in grey. Both present in the country since the beginning of the detected outbreak there.
What about countries that were able to curb the spread of COVID? Was it that they were dealt an easier hand of less transmissible SARS2? This is Singapore, D614G mutation was also detected in February, similar time as several European countries. Strangely, D614G did not dominate.
Visit covidcg.org to play around with the data yourself :) This is Taiwan, another country with exceedingly few COVID cases. They detected D614G as early as March but half a year later their country still hasn't exploded with COVID.
South Korea also saw the D614G mutation in March. In both the "Compare SNVs" (left) and "Compare Lineages" (right) mode, you can see how there were distinct waves of the virus in their country.
Japan also saw D614G early - at the end of January. It's by no means a new mutant of SARS2 for many countries. covidcg.org
Even across Africa, D614G has been around since the beginning. Worth pointing out again that it is not just 1 variant or strain of SARS2 that carries D614G. Many distinct SARS2 variants carry the same G614 mutation on top of several other mutations.
One particularly interesting country is Australia. At first glance it looks like D614G (blue) is dominating again. But turns out the new wave is marked more specifically by an S477N (pink) spike mutation. D614G+S477N were detected in Australia in late Jan. covidcg.org
New Zealand, another country that's done a phenomenal job limiting the spread of COVID. D614G has also been there since the beginning. The country was able to bring the new daily cases of COVID down to mostly single digits by late April.
How about states in the US? State name at top left corner of each picture. G614 in blue; D614 in grey.
US states started seeing D614G by early March. This was after China travel restrictions had been implemented early Feb, but EU travel (conferences!) was still ongoing. The Mar announcement of restrictions caused Americans to stampede back from EU (where D614G was rampant) to US.
“We closed the front door with the China travel ban,” New York Gov. Andrew M. Cuomo (D) said last month as officials began to grasp the magnitude of the failure. In waiting to cut off travel from Europe, he said, “we left the back door wide open.” washingtonpost.com/world/national…
For more ways to use our free and awesome resource @covidcg covidcg.org please check out our new preprint: biorxiv.org/content/10.110… enabled by @gisaid data contributed by hundreds of different labs around the world.
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